this might clear up a few things and also, i did not use a bolt-on pulley.
i used a water pump from an fbody/corvette/gto (car style)
you have two options.
the way i did it was i completly pulled off the car style water pump pulley, heated up the shaft, then hammered on the truck pulley (the reason why you see the threads is b/c that is the skinnier truck pulley) just enough to where it lines up with the rest of your accessories.
or
you can pull pulley out some with a puller like this, just enough to where it lines up with the rest of your accessories.
V car style pulley pictured below...
Lance